Adobe Releases Tamarin
Read also the original Press Release

"Unifies Modern Scripting Across Firefox and Flash and Advances Innovation on the Web

Adobe Systems Incorporated and the Mozilla Foundation, announced that Adobe has contributed source code for the ActionScript™ Virtual Machine, the powerful standards-based scripting language engine in Adobe® Flash® Player, to the Mozilla Foundation. Mozilla will host a new open source project, called Tamarin, to accelerate the development of this standards-based approach for creating rich and engaging Web applications.
The Tamarin project will implement the final version of the ECMAScript Edition 4 standard language, which Mozilla will use within the next generation of SpiderMonkey, the core JavaScript engine embedded in Firefox®, Mozilla’s free Web browser. As of today, developers working on SpiderMonkey will have access to the Tamarin code in the Mozilla CVS repository via the project page located at www.mozilla.org/projects/tamarin/ . Contributions to the code will be managed by a governing body of developers from both Adobe and Mozilla. "

Such a great news:

• a major contribution of a commercial corporation to the open-source community
• a step towards unity and standard compliance for the dynamic/behavior layer of the web : javascript .

Eventually we are witnessing the gestation of a greater one, allying the power of Flash and AJAX engines, to be born free for the benefits of all creative web minds !

I remember a competitive analysis done in 2004 by Macromedia to assess the Backbase framework in regards to Macromedia Flex. In the intro of the document the following was stated:
"There are a number of downsides. First and foremost, since the code relies on the web browser, developers extending the Backbase framework are at risk of “death by a thousand cuts” development needing to work around various browser incompatibility issues. As browsers move towards standards compliance, this becomes less of an issue, but it will always remain.
Another drawback of this solution is that it’s limited by the capabilities of the browser. Applications based on Backbase can do what a browser can do, but cannot go beyond that (like runtime drawing of cornered interfaces). If customer feedback indicates that specific functionality should be added to the runtime because there is a real need for it, there is no way for Backbase to do so, since they rely on joint initiatives taken by the browser industry. At this time, there are no joint initiatives, which leaves the roadmap of next generation Backbase applications unclear."

Well things evolved. Backbase is still there, an important player in the AJAX community. They learned to grow a developper community and open up their codebase. And their initial strategy (reliance on open standards) appears quite right on spot, especially after today's announcement (sic!).
No doubt that good old competition continues although taking a new dimension, more in the open :-)
Let's stay tuned !